In general, an airbag, which is a safety device that is inflated at the time of an accident and deployed between an occupant and a structure in a vehicle so as to protect the occupant using cushioning, is mounted in the vehicle.
The airbag is folded several times and accommodated in an airbag housing so as to be mounted in the vehicle, and thereafter, the airbag is covered by an airbag cover.
The airbag is mounted on a steering wheel in order to protect a driver, or mounted at an upper side of a glove box that is disposed in front of a front passenger seat, and the airbag may be installed at various positions.
Therefore, the airbag cover defines a part of an external appearance of the steering wheel, or defines a part of an external appearance of an instrument panel that is provided at an upper side of the glove box.
At the time of a vehicle accident, the airbag is inflated by gas generated by a gas generator, and deployed while breaking through the airbag cover so as to protect the occupant. Therefore, a tear line, which is torn by expansive force of the airbag so that the airbag may be deployed while breaking through the airbag cover, is formed on a back surface of the airbag cover.
However, the tear line needs to be properly torn in order to deploy the airbag in accordance with design intention, but there occurs an over tear phenomenon in which during a process in which the tear line is torn, torsion stress is applied to the airbag cover due to expansive force of the airbag, and thereby, the airbag cover is torn beyond the tear line, and as a result, there is a problem in that the airbag cannot be properly deployed.